Electrolytic device



J 1936- P. ROBINSON E1 AL ELECTROLYTI C DEVI CE Filed Sept. 27, 1932 PRESTON ROBI N 3 ON AN 0 CARLETON SH UG G INVENTORS BY ,7 ATTORNEYS Patented Jan, 21, 1936 UNITED, STATES PATENT OFFICE ELECTROLYTIC DEVICE Przston Robinson and Carleton Shugg, North dams, assignors to Sprague Specialties 00., North Adams, Mass" a corporation of Massachusetts Application September 27, 1932, Serial No. 635.097

The present invention relates to electrolytic condensers especially to those having a highly 9 Claims.

viscous or pasty electrolyte, and generally referred to as dry 'electrolytic condensers.

Dry electrolytic condensers comprise as a rule two metal foil electrodes of is of film-forming material,, for aluminum, tantalum, etc., w be also of film-forming metal of other material. provided with an which at least one instance of e the other may but may consist One or both electrodes are electrolytically formed oxide film and are wound together into a roll with the interposition of a less viscous electrolyte.

spacer which carries a more or The electrolyte as a rule comprises a weak acid and preferably also the salt of a weak acid, for instance boric acid and ammonium borate,

and a proper ionizing agent which as a rule comprises water and a viscous fluid, for instance a polyhydric glycerine or ethylene glycol. The may also comprise one or more to increase its viscosity.

To maintain the proper operating tics of such condensers it is essential alcohol, as electrolyte inert substances characteristo maintain their original moisture content and to prevent access of moisture from the outside evaporation of the water from the as well as electrolyte.

For this reason as well as for mechanical protection and prevention of access of outside contamination, it has been found advis such condensers in containers.

able to seal Various containers have been proposed for this purpose: for

instance, rigid metal containers which sealingly enclose the condenser, or cardboard containers preferably impregnated witha wax,

for instance,

paraffin. In both types of containers as a rule special provisions are taken to keep liquid and air tight those portions of the device where the electrodes, for the purpose of forming the outside terminals or to be connected to outside terminals,

project from the container.

For instance, in

metal containers the projecting portions of the electrodes are surrounded by case of cardboard containers, compound is provided which jecting portions of the electrodes.

gaskets, whereas in as a rule a sealing surrounds the pro- While as stated the containers should provide for a substantially air and moisture-proof enclosure of the condenser, there should be at the same time provided an escape for the gases,

which gases develop during the operation of the condenser as the passage of current through the condenser liberates oxygen and hydrogen at the electrodes. If these gases are not escape, they build up to considerab afforded an 1e pressures 'stroyed.

and may cause the condenser to blow up. Also, such gases form an explosive mixture which might be ignited by a spark occurring in the condenser during its operation, unless the gases were allowed to escape.

Both of the above containers have obvious drawbacks. The rigid metal containers themselves and the sealing and venting means used in conjunction therewith are expensive and represent a large portion of the manufacturing cost of the condenser unit.

While cardboard containers are less expensive, they have the drawback ofinsufiicient mechanical protection, and when the container is damaged, which is quite likely to occur, especially condenser is mounted by means of clamps, the air tightness of the container is de-' Nor do such containers afford sufilcient mechanical protection against denting or of otherwise damaging the condenser during its handling and mounting.

The present invention has for its purpose to overcome the disadvantages of high cost of the metal container and the insuiiiciency in regard to mechanical protection of the cardboard container and to provide a novel construction of a protecting envelope which is simple and cheap, mechanically strong, not subjected to be damaged and protecting the condenser from being damaged and which permits the provision of simple means for the air and liquid tight sealing of the condenser, and for the escape of gases developed in operation.

Our novel construction has also further advantages later to be pointed out.

Our invention also relates to a process for the assembly of condensers in our novel type of envelope and to novel constructional features to be' pointed out.

The invention will be more fully explained with reference to the drawing forming part of this specification, and in which:

Figure 1 is a side elevation partly in section showing a condenser embodying our invention.

Fig. 2 is a perspective view, partly broken away, of a preferred form of metal envelope used in our invention.

Fig. 3 is a side view partly in section showing a condenser in the process of assembly while subjected to compression after being placed in the 50 metal envelope.

Fig. 4 is a top view showing the condenser in the compression clamps after its compression.

Fig. 5 is a top view of the condenser after it has been removed from the clamps, and the ridges 55 formed by the excess material of the envelope are folded over. 7

Fig. 6 is a fractional side view showing the electrode terminal connections with a cross support for same.

Referring to Fig. 1, there is shown an electrolytic condenser for instance a condenser to be used in the filter circuits of radio receiving sets and which comprises two aluminum foil electrodes l and 2, one. of which, for instance electrode I, is provided with an electrolytically formed film.

Interposed between the two electrodes i and 2 is a gauze spacer 3 carrying an electrolyte. The electrolyte comprises, for instance, a solution of ammonium borate and boric acid, and water and glycerine as ionizing agent, and if desired also an inert substance, the electrolyte having a low fluidity, for instance, pasty consistency.

The aluminum foils l and 2 have integrally projecting portions 4-4 to which are riveted by means of rivets 5-5 suitable terminals 6-6 respectively. There is preferably also provided a cross supporting member 1 of insulating material interconnecting the two projections 4-4, which member is riveted to said projections preferably by means of 'the aforesaid rivets 5-5. Such a cross support considerably stiffens the two terminals and provides for their proper spacing.

The envelope 8 consists of a thin metallic sleeve closed at one end, and is preferably a seamless tube having thin metal walls, for instance, an aluminum tube having a wall thickness of the order of .01" to .015". Other metals such as tin can also be used, however aluminum because of its all-round mechanical properties and especially greater strength, is especially suited. To get satisfactory results it is essential that the metal envelope should be collapsible with the exertion of comparatively small pressure, and on the other hand should be sufllciently resistant to mechanical damaging so as to afford suflicient protection for the condenser.

I'he condenser proper, which is assembled in the form of a roll-as a rule of cylindrical crosssectionis placed within the envelope 8, which has a cross-section slightly exceeding that of the condenser, so that the condenser fits easily therein, but without substantial interspace, and which envelope extends at its open end 99 beyond the condenser.

The envelope with the condenser disposed therein is then placed in a fixture (see Figs.- 3 and 4) which consists, for instance, of four complementary movable jaws 20, 2|, 22 and 23 which, when the jaws are closed, outline the shape to be imparted to the condenser. For instance, in the illustration the contour of the compressed condenser is of substantially oblong shape with the short sides rounded. The fixture is also provided with a bottom plate l5, which may be also in the form of a movable jaw member instead of the fixed plate as shown in the drawing.

The jaws are gradually approached to each other simultaneously or in the present case by first closing jaws 20 and 2| and thereby press the envelope together with the condenser to conform to the shape of the cavities. Thereby the envelope surrounds the condenser so that all air space between the condenser and the envelope and also within the condenser is eliminated. It

' should be noted that the compression slightly reduces the contour area of the envelope and the excess material of the envelope is drawn into ridges l2 which are illustrated in the drawing in somewhat exaggerated manner.

After the condenser is compressed, but while still in the fixture, a fluid sealing compound II which hardens in situ is poured by means of a jet as indicated in Fig. 3 (or in any other suitable way) to fill out the extending portion IQ of the envelope and thus cover the condenser.

The compression of the condenser, as has been stated, forces the air out from between the condenser and the envelope and also from the condenser, and as the sealing compound is poured in and hardens while the condenser is held compressed, formation of new air pockets within the condenser or between the condenser and the envelope is prevented. The prevention of air pockets is of great importance for the maintenance of the proper operating characteristics of the condenser,,as ionization of the air and secondary chemical reaction due to the presence of air, may

otherwise deleteriously influence the properties of the condenser.

The escape for the gases which develop during operation of the condenser, is provided by using such sealing compounds, for instance certain types of pitch, which are sufficiently porous to permit the passage of the developed gases, which, 3

however, are not sufficiently porous to permit escape of the water vapor from the condenser (except for minute amounts carried out by the gases) or to admit, to the condenser moisture or impurities from the outside. that this construction also prevents the formation of gas pockets by the gas liberated during operation. The intimate contact of the metallic envelope with the condenser also provides for excellent heat transfer from the condenser to the outside.

The ridges l2-l2 can be flattened out as indicated in Fig. 5. D

Instead of using a four-part jaw, other jaw constructions may be conveniently used.

As will appear, our invention provides for a simple and cheap construction which afiords good mechanical protection of the condenser, insures an air and liquid-tight sealing therefor and permits the escape of gas, which construction eliminates and prevents formation of air and gas pockets within the condenser and between the condenser and envelope, and provides for a good heat transfer from the condenser to the outside.

While we have described our invention with reference to a specific construction, we donot wish to be limited to such construction, but desire the appended claims to be construed as broadly as permissible in view of the prior art.

In the claims the term dry condenser refers to a condenser having a viscous or pasty electrolyte.

What we claim as new and desire to secure by Letters Patent is:

1. In an electrolytic condenser in combination a condenser body comprising two metal foil electrodes and a highly viscous electrolyte interposed between said electrodes, and a protecting envelope comprising a thin-walled metal tube having at least one axially-extending fold, said tube tightly cinching and directly contacting with said body over its entire circumferential area and being closed at one end and projecting beyond the body at its open end, and a sealing compound filling out the space formed by the projecting end of the envelope above the body.

2. An electrolytic condenser comprising in combination a condenser body having two metal foil electrodes and a highly viscous electrolyte interposed between said electrodes, said electrodes It should be also noted having integral projecting portions for their connection to outside terminals, and a stifiening and spacing member of insulating material connected to said projecting portions and a thin-walled metal tube snugly surrounding said body and in intimate contact therewith over its whole circumferential area, said tube having at least one axially-extending fold and being closed at one end and extending beyond the body at its open end, said extending end surrounding said projecting electrode, and a sealing compound which hardens in situ filling out said extending portion of the tube, said electrode portions and stiffening means being fixed in position solely by the hardened compound.

3. An elecrolytic condenser comprising a condenser body of the dry type and a protecting envelope, consisting of an easily collapsible thinwalled metal tube which is open at one end and closed at the other end, said envelope having at least one fold parallel to its axis and girthing said condenser body.

4. An electrolytic condenser comprising a condenser roll of the dry type, a protecting envelope consisting of a collapsible metal tube of approximately .01 inch thickness, which surrounds and intimately girths said condenser roll around its whole circumferential area, said envelope being provided with at least one axially-extending ridge to tension same about the roll.

5. An electrolytic condenser comprising a condenser roll of the dry type, and a protecting envelope consisting of a thin-walled aluminum tube having at least one axially-extending fold and being open at one end and closed at the other end, said metal tube tightly girthing said condenser roll.

6. An electrolytic condenser comprising a condenser body of the dry type, and a protecting envelope consisting of an easily collapsible thinwalled metal tube having at least one axiallyextending fold, said tube being open at one end and closed at the other end, and snugly surrounding and tightly girthing the condenser body, and a sealing compound to seal the open end of the envelope.

7. An electrolytic condenser comprising a condenser roll of the dry type, and a protecting envelope consisting of an easily collapsible thinwalled metal tube cinching said condenser roll and having at least one integral ridge parallel to its axis and formed by the excess material of the envelope when drawn to cinch said condenser roll.

8. An electrolytic condenser comprising a, condenser roll of the dry type, and a. protecting envelope consisting of a collapsible metal sleeve and contacting the side of the roll with a cornerless surface, said envelope having integral axial ridges causing said envelope to press against said roll and to intimately contact therewith around its entire surface area.

9. In the process of manufacturing dry electrolytic condensers, the steps which comprise, assembling into a roll two electrode foils with the interposition of a highly viscous electrolyte, surrounding said roll with a collapsible metal sleeve which fits around said roll and projects beyond at least one end thereof, deforming said sleeve to reduce its cross-sectional perimeter and to uni formly cinch said roll over its entire cylindrical surface, and pouring a sealing compound which hardens in situ into the open end of the sleeve while the condenser is thus compressed.

PRESTON ROBINSON. CARLETON SHUGG. 

